The present invention relates to a lithographic printing plate support and a method of manufacturing a lithographic printing plate support, as well as a lithographic printing plate precursor.
Lithographic printing is a printing process that makes use of the inherent immiscibility of water and oil. Lithographic printing plates used in lithographic printing have formed on a surface thereof regions which are receptive to water and repel oil-based inks (referred to below as “non-image areas”) and regions which repel water and are receptive to oil-based inks (referred to below as “image areas”).
An aluminum support employed in a lithographic printing plate (referred to below simply as a “lithographic printing plate support”) is used in such a way as to carry non-image areas on its surface. It must therefore have a number of conflicting properties, including, on the one hand, an excellent hydrophilicity and water retention and, on the other hand, an excellent adhesion to an image recording layer that is provided thereon. If the hydrophilicity of the support is too low, ink is likely to be attached to the non-image areas at the time of printing, causing a blanket cylinder to be scummed and thereby causing so-called scumming to be generated. In addition, if the water retention of the support is too low, clogging in a shadow area is generated unless the amount of fountain solution is increased at the time of printing. Thus, a so-called water allowance is narrowed.
Various studies have been made to obtain lithographic printing plate supports exhibiting good properties. For example, JP 2011-245844 A discloses a method of manufacturing a lithographic printing plate support which includes a first step for anodizing a roughened aluminum plate surface, followed by pore-widening treatment, and a subsequent step for reanodizing under such conditions that the diameter of micropores may be smaller than that in the anodized film formed in the first step. It is described that a lithographic printing plate obtained by using the lithographic printing plate support has a long press life and excellent on-press developability.